[tip: x86/urgent] x86/purgatory: Disable the stackleak GCC plugin for the purgatory

[tip-bot2 for Arvind Sankar]

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     ca14c996afe7228ff9b480cf225211cc17212688
Gitweb:        https://git.kernel.org/tip/ca14c996afe7228ff9b480cf225211cc17212688
Author:        Arvind Sankar <nivedita@xxxxxxxxxxxx>
AuthorDate:    Mon, 23 Sep 2019 13:17:54 -04:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Mon, 23 Sep 2019 19:48:02 +02:00

x86/purgatory: Disable the stackleak GCC plugin for the purgatory

Since commit:

  b059f801a937 ("x86/purgatory: Use CFLAGS_REMOVE rather than reset KBUILD_CFLAGS")

kexec breaks if GCC_PLUGIN_STACKLEAK=y is enabled, as the purgatory
contains undefined references to stackleak_track_stack.

Attempting to load a kexec kernel results in this failure:

  kexec: Undefined symbol: stackleak_track_stack
  kexec-bzImage64: Loading purgatory failed

Fix this by disabling the stackleak plugin for the purgatory.

Signed-off-by: Arvind Sankar <nivedita@xxxxxxxxxxxx>
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Fixes: b059f801a937 ("x86/purgatory: Use CFLAGS_REMOVE rather than reset KBUILD_CFLAGS")
Link: https://lkml.kernel.org/r/20190923171753.GA2252517@xxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/purgatory/Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile
index 10fb42d..b81b517 100644
--- a/arch/x86/purgatory/Makefile
+++ b/arch/x86/purgatory/Makefile
@@ -23,6 +23,7 @@ KCOV_INSTRUMENT := n
 
 PURGATORY_CFLAGS_REMOVE := -mcmodel=kernel
 PURGATORY_CFLAGS := -mcmodel=large -ffreestanding -fno-zero-initialized-in-bss
+PURGATORY_CFLAGS += $(DISABLE_STACKLEAK_PLUGIN)
 
 # Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That
 # in turn leaves some undefined symbols like __fentry__ in purgatory and not